Conveyer apparatus and control system therefor



Sept. 14, 1954 R. W. SPAFFORD CONVEYER APPARATUS AND CONTROL SYSTEMTHEREFOR Original Filed July 4, 1945 3 Sheets-Sheet l vL J Sept. 14,1954 R. w. SPAFFORD 2,688,933

CONVEYER APPARATUS AND CONTROL SYSTEM THEREFOR Original Filed July 4,1945 3 Sheets-Sheet 2 Aff J 7% XX a? Sept. 14, 1954 R. w. SPAFFORD2,538,933

CONVEYER APPARATUS AND CONTROL SYSTEM THEREFOR Original Filed July 4,1945 3 Sheets-Sheet 3 Patented Sept. 14, 1954 CONVEYER APPARATUS ANDCONTROL SYSTEM THEREFOR RalphW. Spafford, Euclid, Ohio, assignor to TheLouden Machinery Company, Fairfield, Iowa,

a corporation of Iowa Continuation of application Serial No. 719,575,

December 31, 1946, which is a division of application Serial No.603,158, July 4, 1945. This application February 5, 1953, Serial No.335,231

13 Claims. 1

This application 'is a continuation of application Serial No. 719,575,filed December 31, 1946,

whichis a division of the co -pending application of RalphW. Spaflordand C. Wayne Heil,

'Serial No. 603,158, filed July 4, 1945, both applications beingabondonecl. 1

This application relates to conveyor apparatus and control systemstherefor, more particularly to control systems for conveyors moving on anetwork of trackways in which it is necessary to selectively control theoperation of conveyors at desired points along the network of trackways,and it is an object of the invention to provide an improved conveyorcontrol system of this character.

It is a further object of the invention to provide an improved conveyorcontrol system in which conveyors moving on a network. of trackways maybe selectively controlled to make turns from one trackway to another andmay be selectively controlled to stop at desired points along thetrackway network.

Conveyor systems vary from small installations trackway at some otheroint. After a conveyor has moved onto a branch trackway from a trunktrackway, the situation is virtually the same as a single trackway andconveyors moving thereon must be capable of selectively stopping at oneof a plurality of diiierent points along the branch trackway.

In a conveyor system conveyors, whether loaded or empty, begin theirtravel at some point under the control of an operator who determines towhat point in the system a particular conveyor is to go. It is desirablethat the operator be able to .control with exactitude the point tohaving a single trackway upon which a single conveyor is adapted to moveto installations having a number of trunk trackways from which branchtrackways extend at desired intervals with numerous conveyors adapted tomove on the trackway network. In conveyor apparatus having only a singletrackway, it is frequently desirable or necessary that conveyors movingalong the trackway be selectively controlled to stop at different pointson the trackway. That is, one conveyor may be required to stop at onepoint while a-second conveyor may be required to stop at a differentpoint at some other position along the trackway while a third conveyormay be required to stop at still another point along the trackway. Inconveyor systems where there are a plurality of branch trackwaysextending from one ormore trunk trackways, it is necessary to controltrack switches to direct a conveyor from a trunk track-way onto aparticular branch trackway. Here it is necessary and desirable that thetrack switches be selectively controllable so that one conveyor may turnoff of a trunk trackway onto one branch trackway, while a secondconveyor following immediately behind the first will go on through onthe trunk trackway and turn off onto a difierent branch which thatconveyor goes and that after the con veyor leaves the control of theoperator it will follow the pathway determined for it and arrive at thedesired point. This, of course, may involve making one or more turnsrequiring the operation of one or more track switches as well as theoperation of stopping mechanism when the conveyor reaches the desiredpoint. Accordingly, it is clear that control means must be provided onthe conveyor which move along with the conveyor in its travel and whichcan be set by the operator before it leaves his control so that theconveyor will move past track switches which it is not desired tooperate and will send out a control impulse to operate the proper trackswitch and, furthermore, the control means will operate so that theconveyor will move past stopping stations at which it is not intended tostop and will selectively operate the stopping mechanism at the stationwhere it is desired that the conveyor stop.

Adjacent each track switch that controls a change from a trunk trackwayonto a branch trackway and at each point along the trackways where it isdesired to stop a conveyor, it is necessary to have some stationarycontrol apparatus or operating mechanism to co-operate with the controlapparatus on the conveyorl Such stationary apparatus in the case of atrack switch actuates means such as a motor for moving the track switchand in the case of stopping the conveyor controls the driving means forthe conveyor which may be an electric motor, for ex ample. The problemfor which the present invention is an improved solution is one ofselectively operating the control apparatus on the conveyor as well asthe stationary control apparatus at more than one point along thetrackway or to discriminate between the control apparatus at differentpoints.

The invention disclosed in this application will be described inconnection with overhead monorunning on tracks laid upon the groundwithout departing from the spirit and scope of the invention.

In carrying out the invention in one form conveyor apparatus including atrackway and conveyors adapted for movement along the track- 1-5 way areprovided. To control the operation of the conveyors a plurality ofgenerating means for producing a plurality of different frequenciesalong with a plurality of utilization means, each of which is responsiveto one of the generated 2 frequencies, are associated with the trackwayand the conveyors. Means responsive to the conveyor movement arearranged for sequentially "connecting the generating means and theutilization means in individual electric circuits whereby the 2individual utilization means are effectively energized only whenconnected to generating means producing its responsive frequency.

More particularly, in conveyor apparatus including a trunk trackway, aplurality of branch 3 trackways and a plurality of track switches toconnect the branch trackways to the trunk trackway, each conveyor isprovided with a generator .capable of generating one of a plurality ofselected frequencies and adjacent each track 3 switch there is a circuitresponsive to one of the plurality of frequencies for controlling themoveand the circuits are sequentially connected to- .gether by thetrolleys on the conveyors whereby a particular circuit responds tocontrol the track switch movement only when the frequency of thegenerator on the conveyor corresponds to the responsive frequency of theparticular cir- 4 cuit contacted. Each conveyor also includes a circuitwhich is selectively responsive to one of a plurality of frequencies .tocontrol the conveyor propulsion motor and a plurality of generators (arearranged along the trackway where .it is defor embodying the invention;

Fig. 2 is a detailed circuit diagram of a portion of Fig. 1; r

Fig. 3 is a detailed circuit diagram of another portion of Fig. 1; and

- Fig. 4 is a front view of a conveyor shown diagrammatically in Figs.1, 2 and 3.

Referring more particularly to Fig. l, the invention .is shown embodiedin a conveyor system 10 having .a trunk trackway I I and branch track-'ways 12 and 13 extending therefrom at different stations A and B-spacedalong the trunk trackway ll. At station A there is a track switch 14movable between two positions having a straight trackway l5 and a curvedtrackway [6. In one position the trackway l5 registers with the trackwayII to form a through trackway and in the other position the curvedtrackway l6 registers with the trackway l l to form a switch leadingfrom the trackway H to the branch trackway l2. Similarly at. station 35there is a track switch I'i movable between two positions and having astraight trackway l8 and a curved trackway l9. In one position thestraight trackway 18 registers with the trackway H to form a throughtrackway and in the other position the curved trackway I9 registers withthe trackway l l to connect with the branch trackway 13. Two stopstations C and D are arranged along the branch trackway I2 spaced apartfrom each other and two stop stations E and F are similarly arrangedalong the branch trackway l3. It is contemplated by the presentinvention that a conveyor moving along the trunk trackway II will haveits control apparatus predeterminedly set by Y an operator so that theswitch at one of the station A or B will be operated and the conveyorwill be controlled to stop at one of the stations C, D, E or F. Whileonly one trunk trackway and a pair of branch trackways are shown, itwill become apparent from the specification that more than one trunktrackway may be used as well as more than two branch trackways withoutdeparting from the spirit and scope of the invention since the controlsystem is not limited to any number of trunk or branch trackways.

Adapted to move over the trunk and branch trackways is a conveyor 2]which comprises a pair of spaced-apart, trolley wheels 22 and 23 whichrun upon the trackways. Referring to Fig. 4, it will be seen that thetrolley 23 consists of a pair of laterally spaced-apart wheels .24 and25 rotatively supported by shafts on the opposite ends of a U-shapedyoke 26. Each of the wheels 24 and 25 is adapted to run upon thetrackways, for example the trunk trackway I I, which may be an I beam,as shown. The trolley 22 of Fig. 1, while not shown in Fig. 4, issubstantially identi cal with the trolley 23 and from the trolleys 22and '23 the conveyor proper including the conveyor propulsion motor 28and the control apparatus is supported. Also associated with theconveyor are the current-collecting trolleys 30 and 3 (Fig. 4). Thecurrent-collecting trolley 30 consists of a pair of spaced-apart trolleywheels or other types of contacts 32 and 33 and similarly thecurrent-collecting trolley 3| consists of a pair of spaced-apart trolleywheels or contacts 34 and 35 (Fig. 1), the current-collecting trolleysbeing used to supply power to the propulsion motor 28 as well as todirect the control impulses to stop the conveyor and change itsdirection of travel. The spacing between the trolley Wheels 32 and 33and 34 and 35 has a value to beindicated subsequently in thisspecification. Mounted on the conveyor is a control box 29 whichcontains all of the control apparatus carried by the conveyor necessaryto control the conveyor in its movements. The control box contains notonly the control for the it along the trackways, bus bars 36 and 31extend along the trunk trackway I, the bus bars '38 and 39 extend alongthe branch trackway I2 and the bus bars 4| and 42 extend along thebranch trackway I3, suitable bus bar sections also being arranged on thetrack switches I4 and I1, as shown, to supply power to the conveyorwhile moving on the track switches. The'bus bars, as described, form twoconductors of a three-wire three-phase power supply and the "varioustrackways I, I2 and I3 form the other conductors thereof, thethree-phase system be- "ing indicated by the reference characters L1, L2and L3 of which L3 is the trackway and is grounded at all necessarypoints, as shown.

-While a three-phase system has been shown and the invention will bedescribed in connection therewith, it will be appreciated that a twowirealternating current supply or a direct current supp y may be used. Thenecessary power is supplied to the conveyor motor by thecurrentcollecting trolleys 32, 33 and 34, 35 contacting the various busbars, for example the bus bars.

36 and .3! as shown in Figs. 1, 2 and 4.

To move the track switch I4 from one position to the other, athree-phase motor 43 is provided and is adapted to drive a gear 44 whichengages a rack 45 mounted on the track switch. Power is supplied to themotor '43 by means of the contacto-rs I-B and 41, the contactor 46controlling the motor to run in a direction to move the track switch |4so that the curved trackway |6 comes into registry with the trackways IIand I2, whereas the contactor 41 controls the motor 43 to run in thereverse direction tomove the track switch l4 so that the straighttrackway I 5 registers with thetrunk trackway I I. The contactor 46 isprovided with three pairs of contacts 48, 49 and '50 all of which areoperated by a coil 5|, the contactor being normally deenergized and of atype in which the coil 5| must be energized to hold the contacts closed.The contactor 41 is substantially identical with the contactor 46 andincludes a plurality of pairs of .contacts 52, 53 and 54 operated by acoil 55. The contacts 52, 53 and 54 are normally open and are closedonly when the coil 55 is energized, it being necessary to maintain thecoil in the energized condition to hold the contacts closed. Alsoassociated with the track switch I4 to accurately control its finalposition are the limit switches 56 and 51, the limit switch 56'beingnormally open and acting to deenergize the coil 55 thereby opening thecontacts 52 and 53 and stopping the motor 43 when the track switch l4reaches the position where the trackway I5 registers with the trackwayII and the limit switch 51 being normally closed and being actuated bythe track switch I4 to deenergize the coil 5|, thereby opening thecontacts 49 and 5B and stopping the motor 43 when the trackway |6registers with the trackways II and I2.

3 Similarly to the track switch I4 the track switch I! is provided witha three-phase motor 6| which drives a gear :62 engaging a rack 63 formoving the track switch I? from one position to the other. To supplypower to the motor BI the contactors 64 and 65 are provided, thecontactor 64 being adapted to supply power to the motor 6| to drive thetrack' switch I! from the position shown to its position where thetrackway I9 registers with the trackways II and I3 and the contactor 65being adapted to supply power to the motor 6| to move the track switchI! from the position just mentioned to that where the trackway I8registers with the trackway H. The contactor 64 includes the pairs ofcontacts 66, 6'! and 68 and coil 10 whichactuates the contacts from anormally open position to a closed position, the contactor 64 being of atype wherein the contacts are closed only when the coil is energized andwhenever the coil becomes deenergized the contacts open. The contactor65 is substantially identical with the contactor 64 and includes thepairs of contacts II, 12 and I3 arranged to be operated by the coil 14.The contacts II, I2 and 1 3 are normally open and are actuated to theclosed position when the coil 14 is energized and are opened immediatelyupon deenergization of this coil.

To control the stopping of the track switch I! in either of itsoperative positions the limit switches 7-5 and I6 are associatedtherewith, the limit switch I5 being normally closed and arranged toopen to deenergize the coil Ill and consequently deenergize the motor 6|whenever the track switch I? brings the trackway I9 into registry withthe trackways II and I3 and the limit switch '16 being normally open andadapted conveyor 2| embodies within itself the necessary mechanism orapparatus to selectively determine which, if either, of the trackswitches I4 and I! will be operated to determine whether the conveyormoves straight along the trackway II or turns off onto either of thebranch trackways I2 and I3. Accordingly, there is associated with thetrack switch 4 a relay TI having contacts and an operating coil 8| whichis energized by a discriminator 82 brought into effectiveness by thetrolley or current collector 32 as the conveyor approaches the trackswitch I4. Closing the contacts 8|] energizes the coil 5| to operatethemotor 43. The discriminator 8-2 is energized through a controlsection in the bus bar '36 which includes a control conductor 83 spacedbetween and insulated from the bus bar 36 by the insulators 84 and 85.The control conductor 83 thereforehas no energization normally and isenergized only when the trolley wheel 32 contacts it. This controlsection is placed in the vicinity of the track. switch I4 but asufficient distance away from it so that when the control conductor 83is contacted by the trolley wheel 32, the track switch will be movedfrom the position shown to the position where the trackway I6 registerswith the trackways I I and I2 before the conveyor reaches the trackswitch. Similarly to the track switch l4 a relay 8'6 having contacts '81and an operating coil 88 is associated with the track switch I! and isenergized by a discriminator 9| which becomes effective when theconveyor 2| switch IT. The contacts 8'! when closed, are adapted toenergize the coil ID to operate the motor 6|. The discriminator BI isenergized by the trolley wheel 32 whenever this trolley wheel contactsthe control conductor 62 which is spaced between and is insulated fromthe bus bar 36 by the insulators 93 and 94. The control conductor 92 isspaced adjacent to the track switch l! but a suflicient distancetherefrom so that when the conductor 92 is contacted by the trolleyapproaches the track from the position shown to that where the trackway.19 registers with the trackways 11 and E13 before the conveyor reachesthe track switch. Discriminators 82 and 91 co-operate with mechanism onthe conveyor so that only the desired one of the track switches 14 and11 is operated when a conveyor approaches them.

In the interests of simplicity in disclosing a system which embodies theinvention, it is contemplated that the track switches '14 and 1'1 have:normal positions which are the positions shown and that a track switchafter having moved to a position where a conveyor moves from the trunktrackway onto one of the branch trackways, the track switch is movedback to its normal position. To efiectuate this phase of the operationin one instance a control section including a control conductor 95 isassociated with the bus bar 39 and is insulated therefrom by theinsulators 96 and 9'1. Whenever the trolley wheel 3-2 contacts thecontrol conductor 9 5, i. e., the conveyor 21 has moved from thetrackway 11 onto the trackway -12, the coil 55 is energized through acircuit to be described for efiecting the movement of the track switch14 to its normal position. To effectuate this phase of the operation ina second instance the control section which includes the controlconductor 98 is associated with the bus bar 42 and is insulatedtherefrom by the insulators 191 and 1 02,. Whenever the conveyor hasmoved from the trackway 11 onto the trackway 13 and the trolley wheel 33contacts the control conductor 98, the relay coil '14 will be energizedthrough a circuit to be described to efieotuate movement of the trackswitch to its normal position.

I The invention also embodies the principle that the conveyor controlmay be set in a predetermined manner so that after the conveyor hasmoved onto one of the branch trackways it may be selectively controlledto stop at one of a plu rality .of-stop stations, for example, station Cor Don the trackway 12. The conveyor is driven by an electric motor 28which motor is supplied with power from the bus bars and in order tostop the conveyor the power supply to the motor is interrupted by. asuitable switch as will become clear. The control impulses are suppliedto the conveyor for stopping the conveyor motor on trackway 12 by meansof the generators 103 and 104 which will be more completely described.The generator 193 is connected to a control section including a controlconductor 105 associated with the bus bar 38 and insulated therefrom bythe insulators 106 and 10:1 similarly the generator 104 is connected toa control section including a. control conductor 108 associated with thebus bar 38 and insulated therefrom by the insulators 199 and 119. Theconductors 105 and 168 are adapted to be contacted by the trolley wheels34 and 35 and when the trolley wheel 34 contacts these conductors,control impulses are received by the conveyor and through suitablediscriminating apparatus to be described,

the conveyor is stopped at the desired one of the stations and D.Similarly at stations E and F on the branch trackway 13 there aregenerators 112 and 113. The generator 112 is connected to a controlsection including a control conductor 114 which is associated with thebus bar 41 and is insulated therefrom by the insulators 11 and 116. Thegenerator 113 is connected to a control section including a controlconductor 11! also associated with the bus bar 41 and insulatedtherefrom by means of the in sulators H8 and 119. The conductors M4 and111. are adapted to be contacted by the trolley wheels 34 and .35 andwhen contacted by the trolley wheel :34 an impulse is received by theconveyor and through discriminating apparatus the conveyor is controlledto stop at the desired one of .stationsE and F.

The control box 29 mounted on the conveyor 2| includes a motorcontroller 121, a frequency generator 122, a discriminator or receiver123 as well as the choke coils 1.2 4- .and 212.5,, connected,respectively, between the current-collecting trolleys .32 and 33 and 34and 35 and the condensers 12:6 and 121 connected together and groundedat one of their terminals and connected to the midpoints of the chokecoils 1.24 and 12-5 at their other terminals. The function of the chokecoils and the condensers will be indicated more completely throughoutthe specification. The motor controller 121 controls the forward andreverse movements of the conveyor propulsion motor 28, the frequencyagenerator 122 co-operates with the discriminators 82 and 91 to controlthe movements of the track switches 14 and 1 5, and the receiver 123cooperates with the ;generators 103,, 104., 1112 land 1 1-3 to controlthe stopping of the conveyor.

Referring more particularly to Fig. 2,, there is disclosed the circuitelements of the discriminator 82 associated with the track switch 14ad'- jacent station A and the conveyor 2:1 with the frequency generator122 in order to more completely describe the means for operating thetrack switch 14. The frequency generator 122 is mounted on the conveyor21 and comprises an alternating current generator 128 which is capableof generating a range of frequencies varying from one thousand to threethousand cycles per second, for example, depending on its speed ofrotation. While the generator 128 has been shown as .a piece of rotatingmachinery it will be understood that an electron tube circuit may beused, for example, the well known Hartley oscillator. The generator 128has one of its terminals grounded, as shown, and the other terminal isconnected throughconductors 1313 and 296 to the trolley wheel '32."; Thegenerator 128 is adapted to be driven b'y'a single phase alternatingcurrent motor 131 which may be of the repulsion type for simple speedcontrol. Power is supplied to the motor 131 from the source L1 and L2, aresistance 132 being connected in series with the line L2. Theresistance 132 has a plurality of connecting positions a, b, and 0 sothat the line L2 may :be connected to any one of the three positions inorder to determine the speed of the motor 13! and consequently thefrequency generated by the generator 128. When the source L2 isconnected to the point a the speed of the motor and consequently of thegenerator may be such as to generate a frequency of one thousand cyclesper second. When the source L2 is connected to the point b, the speed ofthe motor will be such that the generator will generate a frequency oftwo thousand cycles per second and when the line L: is connected to thepoint e, the generator will generate a frequency of three thousandcycles per second. Y

The discriminator 82 is a frequency responsive device which becomeseffective when the generator 128 is connected thereto by thecurrent-collecting trolley provided the generator is supplying thefrequency to which the discriminator is responsive and is a triggercircuit comprising a, tuned circuit including the inductance 133 andnected through conductors I35 and -I35 a. to the I control conductor 83and one side of the inductance I33 is connected through the conductorI38 to ground or Le. The inductance I33 and the condenser I34 form aseries circuit which is resonant to one of the frequencies generated bythe generator I28, for example, the frequency of one thousand cycles persecond, and is normally isolated and unenergized since the conductor I35 is connected to the control conductor 83 which is insulated from thebus bar 36. Whenever the circuit of the inductance I 33 condenser I34which is made use of to effect ener-- gization of the coil 8I forclosing the contacts 88 of the relay 11 by triggering the tube I 31.

The electron tube I31 which is of the cold cathode glow discharge typehaving a cathode I38, a grid or starter anode I39 and a plate I 48 whenfired ortriggered by a proper voltage appliedto its grid products asurge of current to operate the relay 11. The cathode I38 is connectedto ground and to one side of'the inductance I33 through the conductorsI43 and I33, while the plate I48 is connected to the control conductor83 through a circuit including the conductor I44, the conductor I45, thecoil 8 I, the conductor I45, the conductor I41, the resistor I48 and theconductor I35a. Thus the coil 8| is in a series circuit with the plateI40 and the cathode I 38. Connected between the conductor I36 andtheconductors I35 and I 35a are the resistors I48 and II, the conductor I41being connected to the juncture of these tworesistors. By varying theresistance of the resistors I48 and I5I the voltage applied between thecathode I38 and the fixed at a desired value.

In order to trigger'or fire the tube I 31 the grid I39 is connected tothe juncture of the inductance I33 and condenser I34 through a circuitincluding the resistor I52, the resistor I54 and the conductor I56-andconnected to the juncture of the resistors I52. and I54 is the resistorI53 having its other end connected to the inductance I33 and groundthrough the conductor I55. The resistorsand the condenser I34 isenergized with the frequency correspond-- plate I48 may be I53and I54constitute a potentiometer and thus" by varying the resistance of theseresistors any portion of voltage appearing across the inductancel33 maybe applied to the grid I39. Even though voltage is applied to the plateI40 of the tube I31 there will be no current flow through the tubeunless the triggering voltage is first applied to the grid I33 and it iswell known that in tubes of the type disclosed after the tube has begunto conduct the current continues to flow until the voltage is removedfrom the plate. LAC- cordingly, when the conveyor moves by the controlconductor 83 and the generator I28 is generating a frequency which isnot the resonant frequency of the inductance and condenser I33 and I34,even though the voltage of this frequency as well as the voltage of thebus bar 38 is applied frequency equal to the resonant frequency ,of theinductance I33 and condenser I34 and the our- 10 rent collector 32contacts the control conductor 83, a high voltage appears across theinductance I33 and, accordingly, a high voltage is applied to the gridI39 and the tube I31 conducts current which flows through the coil 8Ienergizing it to close the contacts 88 and thereby effect movement ofthe track switch I4 as will be subsequently described. The choke coilsI24 and I25 have a high impedance to high frequencies and a, lowerimpedance to low frequencies, and the condens-' ers I26 and I21 have alow impedance to high frequencies and a higher impedance to lowfrequencies. Accordingly, the frequency generated by the generator I28tends to leak to ground through a portion of the coil I24 and thecondenser I21 (the frequency of generator I28 is of an intermediatevalue as will be pointed out). Thus the circuit to the controlconductors of the frequency discriminators is completed effectively whenthe rear collector 32 contacts the control conductors of the variousdiscriminators, for example control conductor 83, at which time thecircuit from generator I28 to the discriminators extends directly fromconductor 286 through current collector 32 without extending throughchoke coil I24. However, the impedance of coils I24 and I25 issufficiently low for the power frequency so as to oii'er a low impedancyto this frequency. The voltage of the generator I28 is applied to theinductance I33 and the condenser I34 through thecircuit extending fromgenerator the coil 81 in order to smooth out the voltage fluctuationsapplied to the coil since the tube I31 passes only half wave impulses.The voltage applied to the plate of the tube is the voltage existingbetween the lines L1 and L3 of the three-phase, system and is applied tothe plate of the tube through a circuit extending from the bus bar 36,the current collector 33, the choke coil I24, the current collector 32,control conductor 83, conductor I35a the resistor I48, conductors I41and I 46, the relay coil 8|, conductors I45 and I44, plate I48, thecathode I 38, through the conductor I43 to ground which also correspondsto L3. In other words, the power on the. bus bars for the conveyorpropulsion motor is also used to supply voltage to the plate circuit ofthe tube I31 while the higher frequency voltage of the generator I28 isused to actuate the tube I31.

The discriminator 9| is substantially identical in its circuit elementsto the discriminator described in Fig. 2. and differs therefrom mainlyin that the inductance and the condenser forming the resonant circuitand corresponding to the inductance I33 and the condenser I34 of Fig. 2are of such a, value that the resonant frequency of the circuit in thediscriminator 9I differs from the resonant frequency of the circuit inFig. 2. For example, the resonant frequency of the discriminator 9| maybe two thousand cycles per second so that when the conveyor moves by itand the current collectors contact the control conductor 82, thediscriminator 9| will not function if the frequency generator on theconveyor .is generating one thousand cycles per second, but

cuit tuned to resonate at one frequency will conduct a very much smallerfraction of current 11. when a frequency of one half the resonantfrequency is applied to it.

Referring now to Fig. 3 of the drawings, the conveyor is shown with allof the apparatus mounted thereon in a position after having movedthrough the track switch I4 in the curved position so that the conveyoris moving on the branch. trackway I2.

The conveyor 2! is moved along the trackways by means of a propulsionmotor 28 which has power supplied to it through the conductors I69 andI6 I- from the current collectors 38 and 3! including the trolleys 32,33and 34, 35. In order that the flow of power to the motor 28 is notinterrupted by the control sections which include control conductors andinsulators separating them from the bus bars the spacing of the trolleys32 and 33 and 34 and 35 is such that the trolleys span over the controlsections and are therefore in contact. with the bus bars at all times.To control the flow of power to the motor 28 the relays I62 and H53 areprovided, the relay I62 controlling the motor to run in the forwarddirection and the relay I63 v controlling the motor to operate in thereverse; direction. Since the motor I528. is a three-phase motor, it isonly necessary to reverse any twoof the motor ower leads to reverse itsdirection of operation and since one of the three-phase terminals isgrounded, as shown. the relays I62 and I83 act. to reverse theconnections; from the current collectors. 32 and 34 to the conductorsI60 and I6,I. The relay I62 is. of a type well known in the art andcomprises a. pair of contacts 164- and I65 adapted to be operated. by acoil L66. The contacts I64 and I66 are normally open and, remain closedonly so long as the coil I166: is energized. The: relay I163. issubstantially identical with the. relay I62 and includes the. normallyopen contacts I69 and I.6;1 adapted to; be closed by the coil I68. Thecontacts. I68. and i611 also are closed only so long as the. coil M18,is. energized.

In order that the. contacts of relay I62 may be. held closed so that.the conveyor will move forward along the trackways without supervision,the mechanically" held or latching relay I is associated with the. relayI 62. The relay I18 comprises. a pair of contacts I1 I: adapted to beclosed through the actuation of an over-center toggle. mechanism I12-and two solenoidsv I13 and IN arranged with their movable cores onopposite sides of the toggle mechanism I 12, the cores being biased awayfromthe toggle mechanism as shown. Whenever the coil I13 is energizedthe toggle mechanism I12 is straightened: to close the contacts. I 1I tothereby maintain the relay I162 in the picked-up position and wheneverthe coil L14. is energized the over-center mechanism I12 is tripped todeenergize the relay I62. The opening coil I1 4: of the relay I10 may beenergized through a stop push button I or it may be energized by meansof the receiver I23. To actuate the conveyor to move forwardly withoutthe control of anoperator, the contacts of the automatic push button I16are closed, and to control the conveyor to move forwardly or rearwardlyin small amounts the forward and reverse push buttons I11 and I18 areprovided. The toggle mechanism of relay I10 is tripped automatically sothat the conveyor will stop at the desired point, for example thestation C, by energizing. the coil I14 by means. of the relay I80. whichincludes the contacts I81. and the operating. coil I82. The coil I.82.is adapted to be. energized by means oi the discriminator or receiverI23 wherebyth lscoil can be energized only when desired. a

The receiver I23 is a trigger circuit comprising. an electron tube I81and a resonant circuit-imcluding the inductance I83 and one of the COD:densers I84, I85 and I86 connected in series across L2 and L3. or groundto control the electron tube. Whenever the series circuit is suppliedwith a voltage having the frequencycor-5 responding to the resonantfrequency of the circuit, a high voltage will appear across theinductance I83 which high voltage is used to energize the coil I82 aswill now be explained. The electron tube I81 is of the cold cathode glowdis-- charge type having a cathode I90, a. grid I9,I- and a plate I92.Normallya tube of this type is non conductive even though a voltage isapplied to its plate and the tube. begins to conduct only when a voltageof proper value is applied to its grid-t The coil I82 is mounted in theplate circuit of the tube I81 in order that the coil may be energizedthrough the circuit extending from bus bar- 38' or L2, currentco1lectors 34 and. 35,..conductor 2I I,

resistor I93, conductor I94, coil I82, conductor H95, through the tubeI81, conductor I96 toground or L3. While the circuit describediscomplete and the voltage from L2, to ground is appliedto it there isno current flowing therein since the tube I81 is non-conducting. Theres'mtor I93 is connected to a. resistor I91 which has its other end.connected to ground or L3 and the conductor I94 is connected to thejuncture of the resistors. I93 and- I91 so that any proportion of thevoltage existing between the lines L2 and L3 may be applied tov theplate I92 of the tube- The grid I 9I of the tube is connected to a.resistor 200. which. is connected to the juncture of. the two resistors20! and 202 having their other ends. connected,v respectively, to thejunctu-rebetween. the inductance I83 and one. of the condensers I84, I85and I83 and L3 or ground. The resistors 20I and 202 form a potentiometerso that any desired por-- tion of the voltage existing across theinductance may be applied to the: grid I191. Thus whenever a frequencyof proper value is; applied to the re.-

ceiver, such. as when the collector 34: contacts the control conductorI05. the circuit includi one of the condensers I84, I85 and I;86, andvthe inductance I 83 resonates and a portion of thehigh voltage appearingacross the inductance is all-- plied to the grid I8I. Consequently thetube It! breaks down and conducts current whereby the coil I82 isenergized and: closes the contacts i8-I which in turn energizes; thecoil I14 to trip the over-center mechanism, I112.

The voltage of the proper frequency to place the, various circuits ofthe receiver I23. into reso-- nance isv supplied by the variousgenerators Ill-3:,v I04, II 2 and I- I3. In Fig. 3 only the generatorI04 at stationl) is illustrated and: comprises a. small single-phasemotor 203 adapted to be enregized. from the lines L1 and L3; and asingle-phase generator 20.4 driven, by the motor to generate a frequencyhaving; a value far removed from the. frequencies of the generator i128such as. for. example, ten thousand cycles, per second; As

indicated for the generator I26. the generators I03, I04 and H2, H3 maybeelectron. tube oscillators such. for example, as the Hartleyoscillator. One terminal of the generator is con-- nected to. l orground and the other terminal is connected through a conductor 2-05 tothe control conductor I08. Since the conductor I08 is insulated. from.the bus bar 41,, the frequency generated by the. generator 204- is;normally isolated.

cal with the stop impulse generator I04 except that the frequencygenerated by the generator I03 differs from that generated by thegenerator I04 by a suflicient amount so that the receiver circuit I23will be energized only by the proper one of the generators. Thus thefrequency generated by the generator I03 may have a value of twentythousand cycles per second. .Since the generators H2 and H3 are in adifferent branch trackway, these generators may generate frequenciesequal to those generated by the generators I03 and I04,

respectively, or they may have frequencies en-v tirely different. It isnecessary that the frequency generated by each of the generatorscorresponds to the resonant frequency of one of the circuit combinationsof the inductance I83 and the condensers I84, I85 and I86 and that thefrequencies differ from each other sumciently so that a circuit arrangedto respond to one frequency will not respond to another one.

With the foregoing description of structure in mind, theremainder of thestructure and the operation of the system may best be set forth byconsidering the different aspect of the system as predeterminedlycontrolled conveyors move through it. I

The first type of operation is that of a. conveyor moving along thetrunk trackway I I and having its final position predetermined so thatit will stop at station D. This requires that the track switch I4 bemoved so that the trackway I6 registers with the trackways II and I2 andfurther that the conveyor move past station C without stopping Thediscriminator 82 has its resonant circuit tuned so that it will resonateto a frequency of one thousand cycles per second and, accordingly, thegenerator I28 on the conveyor 2I is set to generate a frequency of onethousand cycles per second. The generators I04 and I03 are assumed to begenerating respectively ten thousand and twenty thousand cycles persecondand the receiver I23 has its resonant circuit made of inductanceI83 and condenser I85 which resonates at a frequency of ten thousandcycles per second.

To start the conveyormoving, the operator pushes the automatic startbutton I16 (Fig. 3) closing the circuit extending from L1 or bus bar 36(Fig. 1) through the current collector 32, the conductor 206, thecontacts of push button I16, coil I13 of relay I10, conductor 201,conductor 208, conductor 209, conductor 2| I, current collector 34 tothe bus bar 31 (Fig-1). This circuitenergizes the coil I13 whichactuates the over-center mechanism I12 thereby closing the contacts "I.Closing the contacts "I energizes the coil I66 through a circuitextending from bus bar 36 through the current collector 32, conductor206, conductor 2I2, closed contacts I1I, conductor 2I3, coil I66,conductor 2I4, conductor 208, conductor 209, conductor 2, and current,

collector 34 to bus bar 31. Energizing the coil I66 pick up the relayI62 and closes the contacts I64 and I65 and since the relay I ismechanically latched the contacts I64 and I65 are maintained closed.Closing the contacts I64 and I65 supplies power to the motor 28 througha circuit extending from bus bar 36 through current collector 32,conductor206, conductor 2 I 5, conductor 2I6, closed contacts I65,conductor I6I to the motor and from bus bar 31 through current collector34, conductor 2, conductor 209, closed contacts I64 and conductor I60 tothe motor 28.

The motor is thereby energized by connecting the conductors 206 and I6Iand conductors 2H and I60 to run in the forward direction.v

As the conveyor moves forward and the current collector 32 contact thecontrol conductor 83, the frequency generated by the generator I28 issupplied to the discriminator 82 through a circuit extending fromthegenerator I28 through conductor I30, conductor 206, current collector32, control conductor 83 and conductor I35a. Since the frequency beingsupplied by the generatorv I28 corresponds to the resonant frequency ofthe inductance I33 and condenser I34, the tube I 31 of discriminator 82fires as already explained and supplies current to the coil 8I whichpicks up the relay 11 and closes the contacts momentarily. Whenever thecurrent collector 32 moves off of the control conductor 83, the tube I31of the discriminator 82 become de-energized and the relay contacts 80open. Closing thecontacts 80 energizes the coil 5I of the relay 46through a circuit extending from L1, through closed contacts 80,conductor 2I1, coil 5| and conductor 2I8 to L2 and effects closing ofthe contacts 48, and 50. Closing the contacts 48 establishes a holdingcircuit for the coil 5| which extends from L1 through closed contacts48, conductor 2I9, the closed contact of limit switch 51, con ductor 2I1through coil 5I and conductor 2I8 to L2. Thus when the current collector32 moves off of the control conductor 83 the relay 46 remains in itspicked-up condition. Through the closed contacts 49 and 50 power issupplied to the operating motor 43 of the track switch I4 through acircuit extending from L1 through the closed contacts 49, conductor 22I,conductor 222 to the motor 43 and from L2 through closed contacts 50,conductor 223 and conductor 224 to the motor 43. The motor 43 isgrounded, as shown for connection to L3 which is also grounded. Theconductor 222 and 224 leading to the motor are thus connected,respectively, to

L1 and L2 to drive the motor 43 in a direction to move the track switchfrom the normal position shown to that where the trackway I6 registerswith the trackways II and I2. As the track switch moves toward theposition indicated the limit switch 56 closes its contacts and when wayI6 and onto the trackway I2, as shown in Fig. 3. When the conveyor hasmoved completely off of the trackway I6 the current collector 33 willcontact the control conductor which effects energization of the coil 55of the relay 41 to cause the track switch to move to its normalposition. The coil-55 is energized through a circuit extending from L1or bus bar 39 through the current collector 32, choke coil I24, currentcollector 33, control conductor 95, conductor 225, conductor 226, coil55 and conductor 2I8 to L2. Since the conveyor i moving the currentcollector 33 contacts the control conductor 95 momentarily and the coil55 is energized only momentarily. However, energizing the coil 55closesi5. switch 58,v conductor 226', coil 55 and conductor 2.l8s tale.The closed contacts 52 and 53 establish a circuit to the track switchmotor 43' from L1 through conductor 228, closed contacts! 52-, conductor2224. to. the motor 43. and from L2 through conductor 229, closedcontacts 53 and conductor 222 to the motor 43. The third connection tothe.- motor is the ground connection. Therefore, the: leads 222 and 224are connected to L2 and L1, respectively, to drive. the motor 43: in thereverse. direction to move the bridge. trackway back. to the:normalposition where the trackway- I5. registers with the trunk trackwayII:. when the track switch reaches this position the. limit switchcontacts 56 are opened thereby interrupt ing the circuitv to. the. coil55 and effecting open.- ing of the, contacts 52, 53' and 54..Accordingly; t e motor 43: stop and the bridge trackway' is in position.for the next-conveyor: to pass; through.

In this phase of operation the conveyor. is predetermined to stop atstation D and, accordingly it moves past. station without stopping aswill. be made clear. When. the: current: collector 35 contacts theycontrol conductor I05 thefrequency being generated by the generator Hi3of twenty thousand cycles per second is applied. to the chokecoil- I25.The choke coils I and I24 are designed in amanner well. understood bythose skilled. in this art. to prevent; substantially allof thefrequency or twenty thousand cycles per second from passing through thechoke coil I25 to the current collector 34 and the bus bar 38: while.permitting the power frequency of sixty cycles per second, for example,to pass without hindrance. Any small amount of the twenty thousand cyclefrequency which does get through the first part. of. the choke coil,from the current collector is by-passed through the condenser I26. toground, the condensers. I26. and I2'I having a low impedance in highfrequency and a high impedance to low frequencies. Therefore, thefrequency of twenty thousand cycles per second, is prevented fromreaching the current collector 3.4., is kept irom the. bus bars, andconsequently can not. afiect. any apparatus at other points in thesystem. When the current collector 34 contacts the control section I05,the choke coil and the condenser again prevent the twenty thousand cyclefrequency fromv reaching the bus bars. inthe. manner just. described.However, this frequency is supplied. to. the receiver L23. from thegenerator I63, through the control. conductor I05, the. currentcollector 34, and. the conductor 2II... The resonant circuit. of thereceiver I23 (inductance I83 and condenser I85) has. .been set to. be.resonant. to. ten'thousand cycles per second and. accordingly it. doesnot. respond to. develop a high voltage and even thou voltage is beingsupplied to. the plate. or tube. I61, as previously described, the tube.will not fire since there i insufiicientvoltage. on. the. grid IOI.Therefore, no control. impulse. is received by the relay coil I82 andthe conveyor moves by station C.

As the conveyor approaches station. D where it is to stop the currentcollector 35 contacts the control conductor I08 (Fig. 3, collector 35shown dotted) The frequency generated. by the gener-- ator 20.4 at.station D. ten thousand cycles. per second can not. reach the currentcollector 34 or the conductor 2M since the choke. coil I-25- has beendesigned to prevent. this; frequency from being passed and whateverportion has a. tendency to pass through the. choke coil. will bebypassed by the condenser I26 togroun'd. When circuit in the receiver,the inductance: m3; and the condenser N15, is tuned to resonate at thefreI-. quency of ten thousand cycles and accordingly the grid IOIi ofthe tube I18? has: a. high voltage: impulse applied to.- it and the tubefires. supplyinga current impulse. to the coil [82. The coil r62 effectsclosing. of the contacts, I81: thereby energizing. the opening coil I'Mof the relay i102 through a circuit extending: from the current col--lector 32?, conductor- 266, contacts. Iiiil', conductor 231, coilI.I:'4,. conductors 20-1, 206,. we and 2I -.I: to they current.collector: and. bus bar 38. Energizing the. coil I74 trips theover-center mech- 'anism. I12 which opens the contacts III* anddeenergizes the coil 1:66; the relay I62 thereby disconnecting, themotor I-28 and stopping the conveyor at station D; The conveyor hassulficient momentum of itsownto move-past the control conductor I08 sothat the energization of the receiver I23 is removed. To start. it.again the operator determines by means of the receiver I23 at whichpoint the conveyor is next destined to stop whereupon the operatorpushes the auto:

'matic forward switch I16 and the-conveyorbegins.

its travel again.

In the event that it is desired to stop the 0013.?

veyor at a point other than at a control station, the operator need onlypush the stop switch H5- which will also. energize the coil II.4.through a. circuit extending; from the current collector 32 throughconductor 206, push button switch I115, conductor 23L coil I-I-4,conductors 2-0.1, 208,, 203 and 2| I- to the current collector 34. Therelay contacts Ill are opened as already described and the conveyorsstop.

If it isnecessary to. move the conveyor. forward.-

a small amount,, i. a, inching forward, the push. button switch I'II isclosed energizing the coil L56. of relay I62 through av circuitextending from bus bars corresponding to? Llthrough current collector32, conductor 206, switchcontacts I-I'I, eonductor 232, coil I66,conductors 214, 208, 209" and 2 H to current collector 34, and bus barscorre sponding to Lzto. supply the motor 23 only so'long as. the switch.I=TI is: held closed. To inch. the conveyor in the reverse direction.the push button. switch. Isl 8 is. closed to energize. the coil I68 oilthe relay I53 through a circuit extending from current collector 3.2,conductor 206, closed con.-

tacts, of, switch HR, conductor 2-3.3, coil I685, conductors 2%,23.83.2119- and 2H to current collector 34. Energizing the coil I268closes the contacts I66 and L6? which supplies power to: the; motor 23through a circuit extending fromcurrent collector .32, conductor 2 05,,conductor: 2 I5,. conductor 234-, closed contacts Iitl, conductor 2-35,,conductor I60. to the motor and from the current collector 34 throughthe conductors, 2, 209', 208, 236-,

closed contacts Hie, conductor 231' and conductor I6I to the motor 28-.Theground'. connection of themotcr is, the. third connection. The motor28- accordingly runs. in. the. reverse direction sincethe conductors..I-IiIi and IfiI- have. been connected to the conductors 111- and L2.instead. of to Liane.

effect this operation the generator I28 on the conveyor is driven at aspeed by the motor I3I to generate a frequency of two thousand cyclesper second, for example, and the generator H2 at station E is generatinga frequency of twenty thousand cycles per second. Therefore, when in itsmovement the current collector 32 contacts the control conductor83adjacent station A, the discriminator 82 does not become operative sinceits resonant circuit is tuned to resonate at one thousand cycles persecond. Therefore, the track switch I4 remains in the position shown andthe conveyor moves through on the trackway I5 and approaches'station B.

As the current collector 32 contacts the control conductor 92 adjacentstation B the frequency of two thousand cycles being generated by thegenerator I28 is supplied through the conductors I39 and 286, thecurrent collector 32, the control conductor 92 and through conductor 238to the discriminator 9I. The discriminator has a resonant circuit and anelectron tube circuit identical with that of discriminator 82, exceptthat the resonant circuit is tuned to resonate at two thousand cyclesper second. Therefore, when the current collector 32fstrikes the controlconductor; 92 the discriminator 3I becomes efi'ective to energize thecoil 88 of the relay 86 and close the contacts 81 momentarily. Closingthe contacts 81 energizes the coil of relay 84' through a circuitextending from L1 through closed contacts 81, conductor 240, coil 18 andconductor 24I to-Lz and effects closing the contacts 68, 81 and 68. Theclosed contacts 66 complete a holding circuit for the coil 10 from L1through closed contacts 86, conductor 239, closed. contacts of the limitswitch 15, conductor 248, coil 1'8 and conductor, 24I to L2. Therefore,when the current collector 32 has moved 01f of the control conductor 92the relay 84 remains in its pickedup position. Theclosed contacts 81 and68.supply power to the motor 8| to shift the track switch I1 from thenormal position shown to that where the trackway I9 registers with thetrackways II and I3 through the following circuit: From L1 throughclosed contacts 61, conductor 242, conductor 243 to the motor 6| andfrom L2 through closed contacts 68, conductor 244 and conductor 245 tothe motor 8|. The ground connection at the .motor makes the thirdconnection and accordingly the motor runs in the direction to shift thetrack switch I1 to its curved position. As the track switch moves thecontacts of the limit switch 16 close and when it reaches the finalposition where theftrackway I9 registers with the traclrway II, thecontacts of the limit switch are opened interrupting the holding circuitto.

the coil 10 previously described. This opens the contacts 86, 61 and 88and stops the motor BI.

The conveyor moves through the switch on the trackway I9 and afterhavingmoved completely through it the current collector 33 contacts thecontrol conductor 98 which effects actuation of the relay 85 to supplypower to the'motor 6| to drive the track switch from its curved positionto the normal position where the trackway I8 regi'sters with thetrackway II. The relay 65 is actu- 18 ated to close the contacts H, 12and 13 by energizing' the coil 14 through a circuit extending from L1,bus bar 42, current collector 32, choke coil I24, current collector 33,control conductor 98, conductor 246, conductor 241, coil 14 andconductor 24I to L2. Closing the contacts 13 completes a holding circuitfor the coil 14 as follows from L1 through conductor 248, closedcontacts 13, conductor 249, closed contacts of limit switch 16,conductor 241, coil 14 and conductor 24I to L2. Accordingly, the relayremains picked up after the current collector 33 moves off of thecontrol conductor 98. Closing the contacts H and 12 supplies power tothe motor 6| through a circuit extending from L1 through conductor 248,closed contacts II, conductor 245 to the motor BI and from L2 throughconductor'25l, closed contacts 12 and conductor 243 to the motor BI. Theground connection atthe motorcompletes the three-phase circuit. Theconductors 243 and 245 are connected to L2 and L1, respectively, wherebythe motor BI runs in the reversedirection to move the track switch backto the normal position. When this position is reached the contacts ofthe limit switch 18 are opened interrupting the hold ing circuit of thecoil 14 thereby effecting opening of thecontacts II, 12 and 13 and as aresultstopping'th'e motor BI.

30 As the conveyor moves along the trackway I3 its current collector 35contacts the control conductor I which is connected to the stopgenerator I I2 at station E. The generator at station E is constructedto generate a frequency of twenty thousand cycles per second. Since theconveyor" is predetermined to stop at station E the receiver I23 on theconveyor has its resonant circuit comprised of inductance I83 andcondenser l84'which combination forms a circuit resonating at twentythousand cycles per second. As previously described for station D, whenthe current collector 35 contacts the control conductor I I4, thefrequency of twenty thousand cycles is prevented from reaching the busbars by means of the choke coil I25 and the condenser I26, and when thecurrent collector 34 contacts the control conductor N4, the twentythousand cycle frequency is also isolated from the bus bars but thefrequency is supplied through the control conductor H4 and.

the current collector 34 to the resonant circuit (inductance I83 andcondenser I84) of the receiver which responds to trigger the tube I81 toenergize the coil I82 which closes the contacts IBI of relay I80 (Fig.3). Closing the contacts I 8| energizes the coil I 14 of themechanically held relay I18 through a circuit already described andtrips the over-center mechanism I12 opening the contacts "I therebydeenergizing the contaotor I65 supplying power to the conveyor motor 28.

. The conveyor accordingly stops, its momentum carrying it beyond thecontrol conductor II4. If it should be desired that the conveyor move tostation F instead of station E it is only necessary to combine theinductance I83 and the condenser I88 on the receiver I23 so that thisresonant circuit responds to the frequency being generated at station Fwhich may be thirty thousand cycles per second,'for example.

The third instance of operation is one in which it is predetermined thata conveyor should move through both stations A and B and continue on thetrunk trackway II to stop at some other station not shown. To effectuatethis condition the generator I28 on the conveyor is ample. v Therefore,as the conveyor approaches station A the discriminator 82 will notfunction since it responds to a frequency-of one thousand cyclespersecond. The conveyor moves on and as it approaches station v l; thediscriminator 9| also refuses :to function since it responds to afrequency of two thousand cycles per second. Accordingly, the conveyorcontinues to move on the trunk trackway -l=| until it reaches anotherstation where-the discriminator responds to a frequency of threethousand cycles per second.

It will be clear that more than two stop sta tions on each branchtrackway may be provided and the conveyor controlled to stop at suchvadditional stations in a manner substantially identical with thosedescribed for stationsD and E.

. The conveyor system has been described with three rangesoffrequencies, a low frequency for power purposes which may be sixtycycles per second or fifty cycles per second, for example, a higherrange of frequencies which may be frequencies of the order of onethousand cycles persecond to control the movement of the track switches,and a third rangeof frequencies-higher than the second and which may bemultiples .of'

ten thousand cycles per second to control the stopping of the conveyor.The frequencies for controlling the movement of the track switches areapplied from ,a generator on the conveyor to the current collectors 32and 33 .and accordingly .are applied to the .bus bars. Therefore, thisrange of frequencies is received by other apparatus throughout thesystem but .sincethe power involved issmall, even though it may bereceived by the conveyorpropulsion motors, for example, no .ill eflectsresult. Since the frequencies generated by. the generators on theconveyors are-of .the orderof one thousand-cycles and multiples thereof,.insufiicient currents from these generators pass through the motorwindings on the coils 1.24 and 125 to produce false operation. Thus inone instance of operation a conveyor destined for trackway l3 mayhaveits collector 32 on control conductor 83 and following immediatelybehind this conveyor there may be a second conveyor destined fortrackway l2. Under these .conditions a circuit is completed from .theone thousand cycle generator of the following .conveyor through one-halfof the choke coils .124 and 1-25, of the following conveyor through thepropulsion windings thereof through one-half .of the coils I24 and I25of the advanced conveyor whose collector 32 is on the conductor .83 andthrough the motor windings of the propulsion motor thereof. since thepropulsion motors are designed to operate on power frequencies, as forexample, sixty cycle power, the windings ofthese motorspresenta veryhigh impedance to the control frequencies .of one thousand .cycles orgreater, The combined impedances of the coils 1.24 and H5 and the motorwindings prevent current from the one thousand cycle generator on thefollowing conveyor from passing thereth-rough in sufficient magnitude toproduce a sufiicient voltagedrop across the resistor Hil to causedischarge or firing of the tube I31. Accordingly, a following conveyordestined for trackway l2, for example, cannot cause a false operation ofthe switch l4 through the. circuits of an advance conveyor destined foranother trackway. In addition to the presence of the high impedanceelements in the indirect circuit discussed above, the condensers I25 andI26 on each conveyor form grounding circuits which would greatly reducethe magni eluding said conveyorborne circuit means and 20 tude :of theundesired current which might otherwise pass through such indirectcircuit... l he conveyor stopping apparatus responds only to frequenciesabove -:ten -;.thousa;nd cyclesper second, .forexample, and thereforewill be 1111-. afiected'by the lower range offrequencies on the: busbars which is :used to .move the track, switches, The conveyor stoppingvfrequencies (third range) are isolated from the system-bus bars first,by ,the insulated control conductors. such as conductor i198 and second,by thechoke coils connected between the current collector trolleys and,therefore, conveyors throughout the systexnother than the one intendedto be stopped remain unaffected. The power in the third range offrequencies is also small and accordingly produces no .ill effects when:it is. received by the conveyor propulsion motor.

Whilea particular embodiment of the -.invention has been shown it ,willbe understood,-of course, that the invention-is not limited theretosince many modifications-may .be made, and itis, therefore, contemplatedby the appended claims, to cover any such. modifications as come withinthe true spirit and scope of the invention.-

Having thus described the invention, what claimed and desired to ,besecured .by Letters Patentis: v

.1. A trackway, a conveyor for travelling along said trackway, apowerbus bar extending along, said trackway, having a plurality.-of.inter1'up-. tions therein located at spaced distinguishableselectee stations alongside said trackway, a plurality of selecteabusbar meana-oneof said means being interposed at an interruption of saidpower bus bar at each of said stations, said bus bar means being inalignment with respect to and insulated from said power bus bar, spaced.control collector means carried by said conveyor and guided to engagesaid power bus bar sub-I stantially-continuously and to engage saidinterposed .bus bar means sequentially as tl'iecollector means travel, aplurality of .distinguishablecircuit means having differing resonancecharacter-, istics located adjacent said stationsand having. first endsthereof electrically connected one each to respective ones of said 'busbar means, conveyor borne circuit vmeansfincluding manually adjustablemeans for adjusting the resonance characteristics thereof electricallyconnected .at one end to'said collector means, the opposite ends of saiddistinguishable circuit means being. electrically connectable totheopposite end of said conveyor borne circuit means whereby .a.resonant control'circuit may be established inonly the circuit means ofa selected station and only upon engagement of the collector .means withthe bus bar means of the selected station, and means included in saidcontrol circuit operably responsive only-to a resonant condition withinsaid circuit to control an operation affectingthe conveyor at theselected station.

2. A conveyor for travelling along a trackway, a power bus bar extendingalong said trackway] having a plurality of interruptions therein locatedat spaced distinguishable vselectee stations: alongside said trackway, a.plurality'of selectee bus bar means, one of-said means being interposedat an interruption of said power bus bar at each of said station-s, saidbus bar means being in alignment with respect to and insulated from saidpower bus bar, spaced control collector means carried by said conveyorand guided to engage said power bus bar substantially con- 21 tinuouslyand to engage said interposed bus bar means sequentially as thecollector means travel;

a plurality of distinguishable circuit means hav-- ing differingresonance characteristics located adjacent said stations and havingfirst ends thereof electrically connected one each to respectiveones ofsaid bus bar means, conveyor bornecircuit means including manuallyadjustable means for adjusting th resonance characteristics thereofelectrically connected at one end to saidcollector means, the oppositeends of saiddistinguisl'iable cuit means and only the circuit means of ase lected station and only upon engagement of the collector means withthe bus bar means of the selected station, and means included in saidcontrol circuit operably responsive only to a resonant condition withinsaid circuit to'control an operation affecting the conveyor attheselected station.

3. A trackway, a conveyor for travelling along said trackway, a powerbus bar extending along said trackway, having a plurality ofinterruptions therein located at spaced distinguishable selecteestations alongside said trackway, a plurality of selectee bus bar means,one of said means being interposed at an interruption of said power busbar at each of said stations, said bus bar means being in alignment withrespect to and insulated from said power bus bar, spaced controlcollector means carried by said conveyor and guided to engage said powerbus bar substantially continuously and to engage said interposed busbar;

means sequentially as the collector means travel, a plurality ofdistinguishable circuit means having differing resonance characteristicslocated adjacent said stations and having. first ends thereof.electrically connected one each to respective ones of said bus barmeans, conveyor .borne circuit,

means including manually adjustable means for adjusting the resonancecharacteristicsthereof electrically connected at one end to saidcollector.

means, the opposite ends of said distinguishable circuit means beingelectrically connectable to the opposite end of said conveyor bornecircuit means whereby a resonant control'circuit may be.

established including said conveyor borne circuit means and only withthe circuit means of a selected station and only upon engagement of thecollector means with the bus bar means of" the selected station, andmeansincluded in said control circuit operably responsive only to-a celuding said conveyor borne circuit means and only the circuit means ofa selected station and 20 collector means resonant condition within saidcircuit to control an operation afiecting the conveyor; at the selectedstation, said circuit means connected to said collector means comprisinga source of A, C, power of adjustable frequency and said circuit meansconnected to saidbus bar means comprising reactive elements of differingreactive value.

4. A trackway, saidtrackway, a said trackway, having a plurality ofinterruptions' therein located at spaced distinguishable a conveyor fortravelling along power bus .bar extending along selectee stationsalongside said trackway, a plurality of selectee bus bar means, one ofsaid means being interposed at an interruption of said power bus bar ateach of said stations, said bus bar means being in alignment withrespect to and insulated from said power bus bar, spacedcontrolcollector means carried by said conveyor:

and guided to engage saidpower busbar sub-Q stantially continuously andto engage said interposed bus bar means sequentially as the collectormeans travel, a plurality of distinguishable circuit means havingdiffering resonance charac-' teristics located adjacent said stationsand havadjustable means for adjusting the resonance characteristicsthereof electrically connected at one end to said collector means, theopposite ends of said distinguishable circuit means being electricallyconnectable to the opposite end of said conveyor borne circuit meanswhereby a resonant control circuit may be established inonly uponengagement of the with the bus bar means of the selected station,

and means included in said control circuit -operably responsive only toaresonant condition within said circuit to control an operation affectingthe conveyor at the selected station, said circuit. means connected tosaid collector meanscom-fl prising reactive means of adjustable reactivevalue.

5. A trackway, said trackway, said trackway, therein located at spaceddistinguishableselectee stations alongside said trackway, a plurality ofa power bus bar extending along selectee bus bar means, one of saidmeans being interposed at an interruption of said power bus bar at eachof said stations, said bus bar means being in alignment withrespect toand insulated from said power bus bar, spaced control collector meanscarried by said conveyor and guided to engage said power bus barsubstantially continuouslyand to engage said interposed bus barmea'nssequentially as the collector means travel, means located ends thereofelectrically connected one each to respective ones of said bus barmeans, conveyor borne circuit means including manually adjust able meansforadjusting the resonance charac{ teristics thereof electricallyconnected at one end to said collector means, the opposite ends of saiddistinguishable circuit means being electrically,

connectable to the opposite end of said conveyor borne circuit meanswhereby a resonant control circuit maybe established including said con-'veyor bornecircuit means and only the circuit means of, a selectedstation and only upon en-.

gagement of the collector means with the busbarmeans of the selectedstation, and means included in said control circuit operably responsiveonly to a resonant condition within said circuit to control an operationaffecting the conveyor at the selected station, said circuit meansconnected to saidqcollector means comprising reactive means ofadjustable reactive value, and said circuit means connected to said busbar means compris ing a source of A. C. cies.

6. A trackway,

power of differing frequena conveyor for travelling along havingaplurality of interruptions a plurality of distinguishable circuit,having diifering resonance characteristics, adjacent said stations andhaving first a pluralityof distinguishable circuit means havingdiffering resonance characteristics located adjacent said stations andhaving first ends thereof electrically connected one each to respectiveones of i said bus bar means, conveyor borne circuit means includingmanually adjustable means for adjusting the resonance characteristicsthereof electrically connected at one end to said collector means, theopposite ends of said distinguishable circuit means being electricallyconnectable to the opposite end of said conveyor borne circuit meanswhereby a resonant control circuit may be established including saidconveyor borne circuit means and only the circuit means of a selectedstation and only upon engagement of the collector means with the bus barmeans of the selected station, and a translating device located on saidconveyor and included in said control circuit and operably responsiveonly to a resonant condition within said circuit to control an operationafiecting the conveyor at the selected station.

'7. A trackway, a conveyor for travelling along said trackway, a powerbus bar extending along said trackway, having a plurality of interruptions therein located at spaced distinguishable selectee stationsalongsid said trackway, a plurality of selectee bus bar means, one ofsaid means being interposed at an interruption of said power bus bar ateach of said stations, said bus bar means being in alignment withrespect to and insulated from said power bus bar, spaced controlcollector means carried by said conveyor and guided to engage said powerbusbar substantially continuously and to engage said interposed bus barmeans sequentially as the collector means travel, a plurality ofdistinguishable circuit means having differing resonance characteristicslocated adjacent said stations and having. first ends thereofelectrically connected one each to respective ones of said bus barmeans, conveyor borne circuit means including manually adjustable meansfor adjusting the resonance characteristics thereof electricallyconnected at one end to said collector means, the opposite ends of saiddistinguishable circuit means being electrically connectable to theopposite end of said conveyor borne circuit means whereby a resonantcontrol circuit may be established including said conveyor borne circuitmeans and only the circuit means of a selected station and only uponengagement of the collector means with the'bus bar means of the selectedstation, and a'plurality of translating devices located one each at therespective stations and sequentially included in said control circuitand operably responsive only to a resonant condition within said circuitto control an operation affecting the conveyor at the selected station.

8. A trackway, a conveyorior travelling along said trackway, apropulsion motor carried by said conveyor, a power bus bar extendingalong said trackway, having a plurality of interruptions therein locatedat spaced distinguishable selectee stations alongside said trackway, aplurality of selectee bus bar means, one of said means being interposedat an interruption of said power bus bar at each of said stations, saidbus bar means being in alignment with respect to and insulated from saidpower bus bar, spaced control collector means carried by saidconveyorand guided to engage said power bus bar substantially continu ously andto engage said interposed bus bar means sequentially as the collectormeans travel, a plurality of distinguishable circuit means havingdiffering resonance characteristics located adjacent said stations andhaving first ends thereof elec trically connectedone each to respectiveones of said bus bar means, conveyor borne circuit means includingmanually adjustable means foradjusting the resonance characteristicsthereof elec-t trically connected at one end to said collector means,the opposite ends of said distinguishable circuit means beingelectrically connectable to the opposite end of said conveyor bornecircuitmeans whereby a resonant control circuit ,may be establishedincluding said conveyor borne circuit means and only the circuit meansof a selected station and only upon engagement of thecollector meanswith the bus bar means of the selected station and means included insaid control circuit operably responsive only to a resonant conditionwithin said circuit to interrupt the flow of electric power to saidpropulsion motor at the selected station.

9. A trackway, a conveyor for travelling along said trackway, aplurality of track switches in said trackway, a power 'bus bar extendingalong said trackway, having a plurality of interruptions therein locatedat spaced distinguishable selectee stations alongside said trackway, aplurality of selectee bus bar means, one of said means being interposedat an interruption of said power bus bar at each of said stations, saidbus bar means being in alignment with respect to and insulated from saidpower bus bar, spaced control collector means carried by said conveyorand guided to engage said power bus bar substantially continuously andto engage said interposed bus bar means sequentially as the collectormeans travel, a plurality of distinguishable circuit means hav-; ingdiffering resonance characteristics located -means of a selected stationand only 'upon engagement of the collector means with the bus bar meansof the selected station, and electric control means individual to saidstations and sequentially included in said control circuit and operablyresponsive only to a resonant condition within said circuit to operatethe corresponding track switch at the selected station.

10. A trackway, a conveyor for travelling along said trackway, a powerbus bar extending along said trackway, having a plurality ofinterruptions therein located at spaced distinguishable selecteestations alongside said trackway, a plurality of selectee bus bar means,one of said means being interposed at an interruption of said power busbar at each of said stations, said bus bar means being in alignment withrespect to and insulated from said power bus bar, spaced controlcollector means carried by said conveyor and guided to' engage saidpowerbus bar substantially continuously and to engage said interposedbus bar means sequentially as the collectormeans travel, a plurality ofdistinguishable circuit means having differing resonance characteristicslocated adjacent'a pluralityof said stations and having first endsthereof electrically connected one each to respective ones of said busbar means, a plurality of partial control circuits having differingresonance characteristicslocated adjacent the others of said stationsand having first ends thereof electrically connected one each torespective ones of said bus bar means, conveyor borne circuit meansincluding manually adjustablemeans for adjusting the resonancecharacteristics-thereof electrically connected at one end to saidcollector means, the opposite ends of said distinguishable' circuitmeansbeing electrically connectable to the opposite'end of said conveyorborne circuit meanswhereby a resonant control circuit may be establishedincluding said conveyor bornecircuit means and only the circuit meansofa selected station and only upon engagement of the collector means withthe bus bar means of the selected station, a translating device carriedby said conveyor and included in said con-' trol circuit and operativelyresponsive only 'to a resonant condition within said circuit to controlan operation affecting the carrier at the selected station, a partialcontrol circuit including manually adjustable means for adjusting theresonance characteristics thereof electrically connected at one end tosaid collector means, the opposite ends of said trackside partialcontrol circuits being electrically connectable to the opposite end ofsaid conveyor borne partial circuit whereby a resonant control circuitmay be established including said conveyor borne partial circuit andonly the partial control circuit of a selected station and only uponengagement of the collector means with the bus bar means of the selectedstation, and a plurality of translating devices located one each at therespective stations having said partial control circuits andsequentially included in said lastmentioned control circuit and operablyresponsive only to a resonant condition within said control circuit tocontrol an operation afiecting said conveyor at the selected station.

11. A trackway, a conveyor for travelling along said trackway, aplurality of track switches in said trackway, a propulsion motor carriedby said conveyor, 2. power bus bar extending along said trackway, havinga plurality of interruptions therein located at spaced distinguishableselectee stations alongside said trackway including track switchstations and stop stations, a plurality of selectee bus bar means, oneof said means being interposed at an interruption of said power bus barat each of said stations, said bus bar means being in alignment withrespect to and insulated from said power bus bar, spaced controlcollector means carried by said conveyor and guided to engage said powerbus bar substantially continuously and to engage said interposed bus barmeans sequentially as the collector means travel, a plurality ofdistinguishable circuit means having differing resonance characteristicslocated adjacent said stop stations and having first ends thereofelectrically connected one each to respective ones of said bus bar meansa plurality of partial control circuits having differing resonancecharacteristics located adjacent said track switch stations and havingfirst ends thereof electrically connected one each to respective ones ofsaid bus bar means, conveyor borne circuit means including manually 26adjustable means for adjusting the resonance characteristics thereofelectrically connected at one end to said collector means, the oppositeends of said distinguishable circuit means being electricallyconnectable to the opposite end of said conveyor borne circuit meanswhereby a resonant control circuit may be established including saidconveyor borne circuit means and only the circuit means of a selectedstop station and only upon engagement of the collector means with thebus bar means of the selected stop station, means included insaidcontrol circuitand operatively responsive only to a resonantcondition within said circuit to interrupt the fiow of electric power tosaid propulsion motor at the selected stop station, a partial controlcircuit including manually adjustable means for adjusting the resonancecharacteristics thereof electrically connected at one end tosaidcollector means, the opposite ends of said trackside partial controlcircuits being electrically connectable to the opposite end of saidconveyor borne partial circuit whereby a resonant control circuit may beestablished including said conveyor borne partial circuit and only thepartial control circuit of a selected track switch station and only uponengagement of the collector means with the bus bar means of the selectedtrack switch station, and electric control means,

individual to said track switch stations and sequentially included insaid last-mentioned control circuit and operably responsive only to aresonant condition within said control circuit to operate thecorresponding track switch at the selected track switch station.

12. A trackway, a conveyor for travelling along said trackway, a powerbus bar extending along said trackway, a plurality of spaceddistinguishable selectee stations located alongside said trackway, saidpower bus bar having a plurality of interruptions therein individualtosaid stations, a plurality of electrical connecting means locatedadjacent said stations and arranged substantially in alignment with andinsulated from said power bus bar at said interruptions, a plurality ofdistinguishable trackside partial circuits having differing resonancecharacteristics located adjacent said stations and having first endsthereof electrically connected one each to respective ones of saidelectrical connecting means, spaced control collector means carried bysaid conveyor and guided to engage and cooperate with said power bus barsubstantially continuously and to engage and cooperate with saidelectrical connecting means sequentially as the collector means travel,a conveyor borne partial circuit including manually adjustable means foradjusting the resonance characteristics thereof electrically connectedat one end to said collector means, the opposite ends of saiddistinguishable partial circuits being electrically connectable to theopposite end of said conveyor borne partial circuit whereby a resonantcontrol circuit may be established including said conveyor borne partialcircuit and only the partial circuit of a selected station and only uponengagement of the collector means with the electrical connecting meansof the selected station, and means included in said control circuitoperably responsive only to a resonant condition within said circuit tocontrol an operation afiecting the conveyor at the selected station.

27 individual to said stations, a plurality of. electrical connectingmeans located adjacent said stations and arranged substantially inalignment with and insulated from said power bus bar at saidinterruptions, a plurality of. distinguishable trackside partialcircuits having difiering resonance characteristics located adjacentsaid stations and having. first ends thereof electrically connected oneeach to respective ones of said electrical connecting means, spacedcontrol collector means carried by said conveyor and guided to engageand cooperate with said power bus bar substantially continuously and toengage and cooperate with said, electrical connecting means sequentiallyas the collector means travel, a con- -veyor borne partial circuitincluding manually adjustable means for adjusting the resonancecharacteristics thereof electrically connected at one end to saidcollector means, the opposite ends of said distinguishable partialcircuits being electrically connectable to the opposite end of saidconveyor borne partial circuit whereby a resonant control circuit may beestablished including said conveyor borne partial circuit and. only thepartial circuit of a selected station and only upon engagement of thecollector means with the electrical connecting, means of the selected.station,

and means included in said control circuit,- 0D- erably responsive onlyto a resonant condition within said circuit to control an operationafiecting the conveyor at. the selected station.

References Cited in the file or this patent UNITED STATES PATENTS NumberName Date 795,600 Franklin et al. July 25, 190.5 884,630 Bauer Apr. 14,19.08

1,234,492 Rosenwinkel. et al. July 24,1917 1,544,882 Bethenod July 7.,1925 1,797,651 Gergacsevicks et al. Mar. 24, 1931 1,797,864 Harlandtv.Mare. 24, 1931 1,817,692, Kloss et al. Aug. 4,1931 1,871,724 Moss Aug.16', 19-32 1,962,546 Wooley et. al.. i J une. 12,1934 2,254,285 Harriset a1; Sept. 2,. 1941 2,385,917 Harwood et al. Oct. 2., 19.45 2,392,417Spafiord July a, 1946 2,486,221 Spaiford Oct. 25, 1949 2,486,222Spafiord ,1 Oct. 25, 1949 FOREIGN PATENTS Number Country Date- GreatBritain printed 192.8

